Hair straightening and acute kidney injury: a case series from a medical toxicology service.

Background: Formaldehyde-free, glyoxylic acid-containing hair-straightening treatments have gained popularity, but their safety is unproven. Since 2019, our medical toxicology service has identified multiple cases of acute kidney injury following exposure to these products. This study explores the association between glyoxylic acid-based hair-straightening treatments and nephrotoxicity.

Methods: A retrospective study was conducted between April 2021 and March 2025 at Sourasky Medical Center, Tel Aviv, Israel. Thirteen female patients with symptoms such as nausea, vomiting, and abdominal pain that developed following exposure to glyoxylic acid-containing hair-straightening products were evaluated. Data on demographics, clinical presentation, laboratory results, and management were collected, including toxicological investigation of product ingredients.

Results: The mean age of patients was 22 years. Twelve of 13 patients developed acute kidney injury. Urinalysis revealed calcium oxalate crystals in 27% of patients. All patients received intravenous fluids, and eight (61.5%) were treated with thiamine and pyridoxine; the patient who received early treatment did not develop kidney injury. None of the patients required hemodialysis, and there were no deaths. A common feature among the implicated products was the presence of glyoxylic acid, which was potentially linked to the formation of calcium oxalate crystals and subsequent kidney damage.

Discussion: These findings highlight a potentially underrecognized risk of kidney toxicity associated with glyoxylic acid-containing hair products. The consistent clinical presentation, presence of urine calcium oxalate crystals, and temporal association with product use suggest a causal relationship. Prompt recognition and early treatment, particularly with thiamine and pyridoxine, may reduce the severity of kidney damage. Further studies and regulatory action are needed to better define the risk and prevent future cases.

Conclusions: This case series suggests an association between glyoxylic acid hair-straightening products and acute kidney injury, and a potential role for thiamine and pyridoxine in mitigating toxicity. Early intervention may reduce the extent of kidney damage.